This avalanche, seen in a photo taken by one of three skiers carried 300 feet downhill by it, swept over the Lipps Ridge in Turnagain Pass on Thursday. The skiers were unhurt but avalanche danger still exists in the area headed into the weekend. (From CNFAIC)

Three skiers were swept downhill during a Turnagain Pass avalanche Thursday but escaped the slide unharmed. Authorities say the incident is a warning that avalanche danger persists in the area.

According to a Chugach National Forest Avalanche Information Center report posted Thursday evening, the skiers were ascending the Lipps Ridge on an upward track and had reached an elevation of 2,300 feet when they were struck and carried 300 feet downhill. All three, however, "ended up on the surface of the debris after being swept down."

"The avalanche was triggered from below and propagated above them," forecasters wrote. "It is believed to be a persistent slab that likely failed in the weak faceted snow from pre-Christmas."

Aleph Johnston-Bloom, an avalanche forecaster with the center, said the slide happened between 1:30 and 2 p.m. on the east side of the Seward Highway in an area designated for non-motorized recreational use.

"It was actually observed from the road," Johnston-Bloom said. "Somebody had stopped to observe the terrain, saw them going up, and then saw a powder cloud and didn't see them."

That person called Alaska State Troopers, who responded along with U.S. Forest Service Law Enforcement personnel and forecasters from the avalanche center. When they arrived, however, the skiers — who had rescue equipment on them during the avalanche — were returning from the slide area unhurt.

"They lost some of their equipment and walked out," Johnston-Bloom said.

Johnston-Bloom said the "persistent slab" refers to a "slab of snow on top of weak snow that can stay on top for weeks at a time."

She added that the incline at the avalanche site was between 35 and 40 degrees, which also contributed to the avalanche danger.

In the Chugach, a Friday avalanche advisory for the Turnagain area called for considerable avalanche danger at elevations above 2,500 feet and moderate avalanche danger between 2,500 feet and 1,000 feet. The Hatcher Pass Avalanche Center listed considerable avalanche danger above 2,500 feet, as well as moderate avalanche danger below that elevation.

The site of Thursday's slide is still prone to further avalanches, Johnston-Bloom said.